Apparatus for manufacturing micro-structure

ABSTRACT

A substrate on which a plurality of thin films having a plurality of cross-sections corresponding to the cross-section of a micro-structure are formed is placed on a substrate holder. The substrate holder is elevated to bond a thin film formed on the substrate to the surface of a stage, and by lowering the substrate holder, the thin film is separated from the substrate and transferred to the stage side. The transfer process is repeated to laminate a plurality of thin films on the stage and to form the micro-structure. Accordingly, there are provided a micro-structure having high dimensional precision, especially high resolution in the lamination direction, which can be manufactured from a metal or an insulator such as ceramics and can be manufactured in the combined form of structural elements together, and a manufacturing method and an apparatus thereof.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to micro-structures such as micro-gears,micro-optical parts, or molds for molding these micro-productsmanufactured by rapid prototyping, and a manufacturing method and anapparatus thereof, and more particularly relates to micro-structuresobtained by laminating thin films consisting of a metal or an insulatorwhich are patterned into sectional forms, and a manufacturing method andan apparatus thereof.

[0003] Rapid prototyping has been rapidly popularized recently as amethod for molding three dimensional complex form products designed withaid of a computer within a short time. Three dimensional productsmanufactured by rapid prototyping are used as parts models (prototype)of various apparatus to predict the suitability of operation or form ofparts. This method has been mainly applied to relatively large partshaving a size of several cm or larger, however, recently it has beendesired to apply this method to manufacture micro-parts formed byprecise working such as micro-gears and micro-optical parts.Conventional methods for manufacturing such micro-parts describedhereinafter have been known.

[0004] (1) Stereolithography (referred to as “conventional example 1”hereinafter)

[0005] (2) Selective laser sintering (referred to as “conventionalexample 2” hereinafter)

[0006] (3) Sheet lamination (referred to as “conventional example 3”hereinafter)

[0007] (4) Method using thin films as starting material (referred to as“conventional example 4” hereinafter)

[0008] (Convention example 1)

[0009]FIG. 26 shows the conventional example 1 namely thestereolithography. In the “stereolithography”, photo-curable resin 100,which is hardened by irradiation of light such as ultraviolet rays, isfilled in a tank 101, a laser beam 102 scans on the surface of the tank101 two-dimensionally to draw a form corresponding to thecross-sectional data of a three-dimensional product to harden the resinlayer 100 a, then a stage 103 is lowered by one layer, and this processis repeated layer by layer to form the three dimensional productcomprising a plurality of resin layers 100 a. Stereolithography ispresented by Ikuta, Nagoya University, in a literature “OPTRONICS, 1996,No. 4, p 103”. According to the special stereolithography, planer formprecision of 5 μm and resolution in the lamination direction of 3 μm canbe attained by optimization of exposure conditions and optimization ofresin characteristics. Stereolithography is also presented by Kawata,Osaka University, in a literature “Proceedings of MEMS 97, p169”.According to this stereolithography, planer form precision of 0.62 μmand resolution in the lamination direction of 2.2 μm can be attained byutilizing a principle of two-photon absorption phenomenon.

[0010] (Conventional example 2)

[0011]FIG. 27 shows the conventional example namely selective lasersintering. In the “selective laser sintering”, powder 104 is laid toform a thin layer (powder layer) 104 a a laser beam 102 is applied tothe powder layer 104 a to form a thin layer of a desired form, and byrepeating this process a three dimensional sintered product composed ofa plurality of powder layers 104 a is formed. According to the selectivelaser sintering, a three dimensional product not only of resin but alsoceramics and metals can be formed.

[0012] (Conventional example 3)

[0013]FIG. 28 shows a manufacturing apparatus used in the conventionalexample 3 namely the sheet lamination disclosed in Japanese PublishedUnexamined Patent Publication No. Hei 6-190929. In this manufacturingapparatus, when a plastic film 111 is supplied from a film feedingdevice 110, an adhesive coating device 120 coats photo-curable adhesive121 evenly on the underside of the plastic film 111 to form an adhesivelayer, a negative pattern exposure device 130 exposes an area of theadhesive layer excepting the area corresponding to the cross sectionalform of a micro-structure to form the hardened portion and the uncuredportion, this is pressed down by a press roller 141 of a photo-curinglaminating device 140, the uncured portion is hardened by the light froma light source 142 and bonded to the lower plastic film 111. The rearend of the plastic film 111 is cut by a laser beam from a CO₂ lasersource 151, and the border of the unnecessary area of the uppermostplastic film 111 is removed by the laser. This process is repeated layerby layer to form a micro-structure. In FIG. 28, 160 represents a workdevice for controlling this apparatus. According to the sheetlamination, a micro-structure comprising plastic sheets is obtained.

[0014] (Conventional example 4)

[0015]FIG. 29 shows the conventional example 4 namely a manufacturingmethod using thin films as starting material disclosed in JapanesePublished Unexamined Patent Publication No. Hei 8-127073. In thismanufacturing method, as shown in the drawing (a), a photosensitiveresin film 171 is formed on a substrate 170, and two processes, namely aprocess for forming an exposed portion 171 a by exposing on an area of adesired pattern as shown in the drawing (b) and a process for forming anintermediate film 172 which prevents the resin film 171 from being mixedand prevents exposure of the lower layer, are repeated to form amulti-layer structure composed of the resin film 171 and intermediatefilm 172 as shown in the drawing (c), and then the exposed portion 171 ashown in the drawings (b) and (c) is selectively removed by dipping itin a resin developing solution and thus a three dimensionalmicro-structure as shown in drawing (d) is obtained. According to thismanufacturing method, the resolution in the lamination direction of μmorder can be attained because spin coating is applied to the resin film171 and intermediate film 172.

[0016] However, according to the conventional example 1, namelystereolithography, this method is disadvantageous in that the resolutionin the lamination direction of 1 μm or smaller and the film thicknessprecision of 0.1 μm or smaller, which is required to manufacturemicro-gears and micro-optical parts, cannot be attained. In detail,because an incident light applied perpendicularly onto the layer forhardening the starting material (photosensitive resin) is used, theincident light penetrates perpendicularly from the surface through thelayer with decreasing intensity due to absorption, and the intensitydecreases to the level of threshold value required for curing. The layerthickness corresponding to the threshold value is the thickness of onelayer, but because of dispersion of the incident light intensity,variation of the incident light intensity with time, and dispersion ofthe absorption coefficient of the starting material, it is difficult toobtain high resolution.

[0017] In addition, full cure process is applied to harden completelyafter forming because photosensitive resin is used, in the full cureprocess the product shrinks 1% through several %, the shrinkage isdisadvantageous and causes significant deterioration of the precision.

[0018] Furthermore, this method can be applied to only micro-structuresmade of relatively soft photosensitive resin, therefore, if amicro-structure is required to be made of a hard material such as ametal, the only way to manufacture the product is the molding byelectroforming or injection molding using a mold of this resin. Therequirement of such process is disadvantageous.

[0019] According to the conventional example 2, namely the selectivelaser sintering, the resolution in the lamination direction is poorbecause an incident light applied perpendicularly onto the layer is usedas in the conventional example 1, and the shrinkage in full cure processcauses deterioration of precision, and furthermore the method isdisadvantageous in that a transfer process is required to manufacturemicro-structures made of a hard material such as metal.

[0020] According to the conventional example 3, namely the sheetlamination, the sheet thickness is the determinant factor of theresolution in the lamination direction, the lower limit is about severaltens μm in view of usable sheet thickness, and it is difficult torealize the resolution in the lamination direction of 1 μm.

[0021] According to the conventional example 4, namely the manufacturingmethod using thin films as starting material, the intermediate film (forexample A1) is required in order to prevent exposure of the lower layerbecause an incident light applied approximately perpendicularly is usedin the exposure process, this method is disadvantageous in theresolution per one layer. Though a method in which two types ofphotosensitive resins of different sensitive wavelengths and differentsolubility in solvents are laminated alternately, the respectivephotosensitive resins are exposed, and finally developed to form a threedimensional product in order to omit the use of the intermediate film,is disclosed in the patent, because this method is still disadvantageousin that the adhesion between resins of different solubility in solventsis poor, the strength of a completed product is low, and the dimensionalprecision is poor due to swelling of the photosensitive resin in thefinal development process. Furthermore, it is impossible to apply thismethod directly to hard material such as metals and insulators as in theabove-mentioned stereolithography because photosensitive resin is used,and the only way is a method in which a product is used as a mold.

[0022] Accordingly, it is an object of the present invention to providemicro-structures of high dimensional precision and, particularly, highresolution in the lamination direction and a manufacturing method and anapparatus thereof.

[0023] It is another object of the present invention to providemicro-structures which are formed directly of metals or insulators suchas ceramics and a manufacturing method thereof and an apparatustherefor.

[0024] It is yet another object of the present invention to providemicro-structures which can be formed together from a plurality ofcombined structural elements and a manufacturing method and an apparatusthereof.

SUMMARY OF THE INVENTION

[0025] To achieve the above-mentioned object, the present inventionprovides a micro-structure comprising a plurality of laminated thinfilms having prescribed two-dimensionally patterned forms.

[0026] To achieve the above-mentioned object, the present inventionprovides a manufacturing method of micro-structures composed of a firststep for forming a plurality of thin films having prescribedtwo-dimensionally patterned forms on a substrate, and a second step forforming the micro-structure by separating the plurality of thin filmsfrom the substrate and subsequently by laminating and bonding theplurality of thin films on a stage.

[0027] To achieve the above-mentioned object, the present inventionprovides a manufacturing method of micro-structures including;

[0028] a first step for forming a plurality of first thin films having aprescribed two-dimensional pattern on a substrate, and forming aplurality of second thin films composed of different material from thatof the first thin films and having the same film thickness as the firstthin film to form a plurality of composite thin films comprising thefirst thin films and the second thin films,

[0029] a second step for forming a laminate including a micro-structureby laminating and bonding the plurality of composite thin films on astage, and

[0030] a third step for removing the first thin films or the second thinfilms out of the substrate to obtain the micro-structure.

[0031] To achieve the above-mentioned object, the present inventionprovides a manufacturing method of micro-structures including;

[0032] a first step for forming a thin film respectively on a pluralityof substrates and forming a plurality of latent images having aprescribed two-dimensional pattern on each thin film formed on theplurality of substrates,

[0033] a second step for bonding the thin films each other on which thelatent images are formed,

[0034] a third step for removing one substrate out of a pair ofsubstrates having the thin films bonded each other,

[0035] a fourth step for laminating a plurality of thin films byrepeating the second step and the third step, and

[0036] a fifth step for developing the latent images out of theplurality of laminated thin films.

[0037] To achieve the above-mentioned object, the present inventionprovides a manufacturing apparatus of micro-structures provided with;

[0038] a substrate holder having a substrate on which a plurality ofthin films are formed thereon having a prescribed two-dimensionalpattern provided in a vacuum chamber,

[0039] a stage disposed facing the substrate holder in the vacuumchamber for supporting a three-dimensional structure formed bylaminating the plurality of thin films,

[0040] a moving means for transferring at least either of the substrateholder and the stage to position the stage successively on the pluralityof thin films, and

[0041] a control means for controlling the moving means to separate theplurality of thin films from the substrate, to laminate and bond theplurality of thin films on the stage so as to form a micro-structure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042]FIG. 1 is a block diagram for illustrating a manufacturing systemin accordance with the first embodiment of the present invention.

[0043]FIG. 2 is a schematic structural diagram of a lamination equipmentin accordance with the first embodiment.

[0044]FIG. 3 is a block diagram for illustrating a control system of thelamination device in accordance with the first embodiment.

[0045]FIG. 4 is a diagram for describing the relation between thebonding strength of a sacrifice layer, a thin film, and a releasinglayer in the first embodiment.

[0046]FIG. 5 is a perspective view of a target micro-structure of thefirst embodiment.

[0047]FIG. 6 is a set of diagrams, FIG. 6(a) shows a thin filmdeposition process in accordance with the first embodiment, and FIG.6(b) and FIG. 6(b) show the patterning process in accordance with thefirst embodiment.

[0048]FIG. 7 is a set of diagrams, FIGS. (a) through (c) show thelamination process in accordance with the first embodiment.

[0049]FIG. 8 is a set of diagrams, FIGS. (d) through (f) show thelamination process in accordance with the first embodiment.

[0050]FIG. 9 is a cross-sectional view for showing completion of alamination process in accordance with the first embodiment.

[0051]FIG. 10 is a set of diagrams, FIG. 10(a) is an explodedperspective view of a micro-pulley, namely a micro-structure, and FIG.10(b) is a cross-sectional view of the micro-pulley.

[0052]FIG. 11 is a set of diagrams, FIGS. 11(a) through (e) show thefilm deposition and patterning process in accordance with the secondembodiment.

[0053]FIG. 12 is a plan view of a substrate for showing the patterningprocess in accordance with the second embodiment.

[0054]FIG. 13 is a plan view of a substrate for showing the patterningprocess in accordance with the second embodiment.

[0055]FIG. 14 is a cross-sectional view for showing laminatedcross-sectional elements of the first layer through twentieth layer inaccordance with the second embodiment.

[0056]FIG. 15 is a set of diagrams, FIG. 15(a) is an explodedperspective view of a target micro-gear of the second embodiment, andFIG. 15(b) is a longitudinal cross-sectional view of the micro-gear.

[0057]FIG. 16 is a plan view for showing a thin film depositionsubstrate in accordance with the third embodiment of the presentinvention.

[0058]FIG. 17 is a set of diagrams, FIGS. 17(a) through (d) are planviews for showing a thin film deposition substrate in accordance withthe third embodiment of the present invention.

[0059]FIG. 18 is a cross-sectional view for showing laminated chips ofthe first layer through twentieth layer in accordance with the thirdembodiment.

[0060]FIG. 19 is a schematic structural diagram of the patterningequipment in accordance with the fourth embodiment of the presentinvention.

[0061]FIG. 20 is a perspective view of a target micro-structure of thefourth embodiment.

[0062]FIG. 21 is a plan view of a substrate for showing the patterningprocess in accordance with the fourth embodiment.

[0063]FIG. 22 is a cross-sectional view for showing laminatedcross-sectional elements of the first layer through n-th layer inaccordance with the fourth embodiment.

[0064]FIG. 23 is a block diagram for illustrating a manufacturing systemin accordance with the fifth embodiment of the present invention.

[0065]FIG. 24 is a set of diagrams, FIGS. 24(a) through (d) are diagramsfor showing a manufacturing method in accordance with the fifthembodiment.

[0066]FIG. 25 is a set of diagrams, FIGS. 15 (e) through (h) arediagrams for showing a manufacturing method in accordance with the fifthembodiment.

[0067]FIG. 26 is a schematic diagram for illustrating thestereolithography of the conventional example 1.

[0068]FIG. 27 is a schematic diagram for illustrating the selectivelaser sintering of the conventional example 2.

[0069]FIG. 28 is a diagram for illustrating a manufacturing apparatus inaccordance with the sheet lamination of the conventional example 3.

[0070]FIG. 29 is a set of diagrams, FIGS. 29(a) through (d) show amanufacturing method of the conventional example 4 in which thin filmsare used as starting material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0071]FIG. 1 shows a manufacturing system of micro-structures inaccordance with the first embodiment of the present invention. Thestructure of this manufacturing system 1 comprises a film depositionequipment 2A for depositing a thin film on a substrate, a patterningequipment 2B for patterning a pattern on the thin film formed by thefilm deposition equipment 2A corresponding to cross-sectional forms ofan object micro-structure, and a lamination equipment 3 for laminating aplurality of patterned thin films by surface activated bonding.

[0072] The film deposition equipment 2A controls excellently the filmthickness of a film deposited on a substrate such as an Si wafer, aquartz substrate, or a glass substrate (for example, Corning 7059) in athickness range from sub μm through several μm, and forms a thin filmby, for example, vacuum vapor deposition such as electron beamdeposition, resistance heating vapor deposition, sputtering, or chemicalvapor deposition (CVD), or spin coating which gives a film with eventhickness through the entire substrate. By applying vacuum vapordeposition or spin coating, a film with a thickness of 0.1 through 10 μmis deposited with a film thickness precision of {fraction (1/10)} thefilm thickness or smaller.

[0073] The film deposition equipment 2A previously forms a releasablereleasing layer on the surface of a substrate prior to deposition orcoating of a thin film. The releasing layer may be a thin film ofthermal oxide or fluorine-containing resin formed by vapor deposition orcoating on the surface of a substrate, or may be formed by a method thatthe substrate surface is exposed to discharge in a gas containingfluorine to fluoridize the substrate surface. The releasability isenhanced by forming a thin film containing fluorine or fluoridation.

[0074] The patterning equipment 2B forms a plurality of thin filmshaving forms respectively corresponding to each cross-sectional form ofa micro-structure by removing unnecessary portions or circumferencetogether using a patterning method for patterning with a planerprecision within 0.1 μm, for example, photolithography, focused ion beammethod (FIB), or electron beam lithography. By applying lithography, theplaner precision of sub μm is obtained, and the productivity isenhanced. By applying FIB method and electron beam lithography, theplaner precision of sub μm is obtained, and a film is patterned withoutusing a photo-mask because an arbitrary form is drawn by beam scanning,hence the time for manufacturing of photomasks is saved. In the case ofthe electron beam lithography, electron beam resist which is sensitiveto an electron beam is used as the resist. In the first embodiment,unnecessary portions are removed by photolithography.

[0075]FIG. 2 shows a schematic structure of the lamination equipment 3.The lamination equipment 3 is provided with a vacuum chamber 300 inwhich lamination process is performed, and in the vacuum chamber 300, asubstrate holder 301 on which a substrate 400 is placed and fired, astage 302 to which a thin film formed on the substrate 400 istransferred, the first FAB source 303A for FAB (Fast Atom Bombardment)of the stage 302 side and the second FAB source 303B for FAB of thesubstrate 400 side both attached to the stage 302, the first and secondwithdrawing motors 305A and 305B for withdrawing the first and secondFAB sources 303A and 303B by rotating arms 304A and 304B about 90° afterFAB, a mark detection unit 306 for detecting an alignment mark on thesubstrate 400 as a microscope mounted on the stage 302, a vacuum gauge307 for measuring the degree of vacuum in the vacuum chamber 300, anX-axis table 310 for moving the stage 302 in the X-axis direction(horizontal direction in FIG. 2) using an X-axis motor 311 (refer toFIG. 3) and for detecting the position of the stage 302 on the X-axisusing an X-axis position detection unit 312 (refer to FIG. 3), and aY-axis table 320 for moving the stage 302 in the Y-axis direction (inthe direction perpendicular to the page plane) using a Y-axis motor 321(refer to FIG. 3) and for detecting the position of the stage 302 on theY-axis are provided. Herein, “FAB” means a treatment that, for example,argon gas which is accelerated by a high voltage of about 1 kV isapplied onto the surface of a material as an atom beam to remove oxidefilm and impurities on the material surface and to clean the surface. Inthis embodiment, the FAB irradiation conditions are varied depending onmaterial to be treated, in detail, the acceleration voltage is varied ina range from 1 through 1.5 kV, and irradiation time is varied in a rangefrom 1 to 10 minutes.

[0076] The stage 302 consists of a metal such as stainless steel oraluminum, and a sacrifice layer is formed previously on the surface inorder to separate the micro-structure easily from the stage 302 themicro-structure comprising a plurality of thin films laminated on thestage 302. Material used for the sacrifice layer is selected dependingon the material of the micro-structure. In detail, for themicro-structure made of a metal such as aluminum, copper or nickel isselected as the material of the sacrifice layer, and in this case, acopper or nickel layer with a thickness of, for example, about 5 μm isformed on the surface of the stage 302 by plating. For themicro-structure which comprises thin films of an insulator, namelyceramics such as alumina, aluminum nitride, silicon carbide, or siliconnitride, aluminum is selected as the material of the sacrifice layer,and in this case, an aluminum layer is formed on the surface of thestage 302 by vacuum vapor deposition. By removing only the sacrificelayer after completion of thin film lamination, the micro-structure isseparated easily from the stage 302 without an external force applied tothe micro-structure.

[0077] The lamination equipment 3 is provided with a Z-axis table 330, aθ table 340, a vacuum pump 350, an argon gas cylinder 351, and the firstand second flow rate controllers (MFC) 353A and 353B. The Z-axis table330 is served for moving the substrate holder 301 in the Z-axisdirection (vertical direction in FIG. 2) to the outside of the vacuumchamber 300 using a Z-axis motor 331 (refer to FIG. 3), for pressing thethin film onto the stage 302 side with a pressure of 5 kgf/cm² or higherfor 1 through 10 minutes, and for detecting the position of thesubstrate holder 301 on the Z-axis using a Z-axis position detectionunit 332 (refer to FIG. 3). The θ table 340 is served for rotating thesubstrate holder 301 round the Z-axis using a θ motor 341 for alignmentadjusting, and for detecting the angular position in the θ-direction ofthe substrate holder 301 using a θ position detection unit 342 (refer toFIG. 3). The vacuum pump 350 is served for evacuating the internal ofthe vacuum chamber 300 to a vacuum. The argon gas cylinder 351 containsargon gas. The first and second mass flow controllers (MFC) 353A and353B is served for controlling the flow rate of argon gas supplied fromthe argon gas cylinder 351, and for supplying argon gas to the first andsecond FAB sources 303A and 303B through the first and second solenoidvalves 352A and 352B.

[0078]FIG. 3 shows a control system of the lamination equipment 3. Thelamination equipment 3 has a control unit 360 for controlling thisequipment 3 wholly, and the control unit 360 is connected to variousunits namely a memory 361 for storing various information includingprograms of the control unit 360, the first FAB source 303A via thefirst FAB source driving unit 362A, the second FAB source 303B via thesecond FAB source driving unit 362B, the first and second withdrawingmotors 305A and 305B, the mark detection unit 306, the vacuum gauge 307,the X-axis motor 311, the X-axis position detection unit 312, the Y-axismotor 321, the Y-axis position detection unit 322, the Z-axis motor 331,the Z-axis position detection unit 332, the θ motor 341, the θpositiondetection unit 342, the vacuum pump 350, the first and second solenoidvalves 352A and 352B, and first and second MFCs 353A and 353B.

[0079] For example, a laser interferometer or glass scale may be used asthe X-axis position detection unit 312, the Y-axis position detectionunit 322, and the θ position detection unit 342.

[0080] The first and second FAB source driving units 362A and 362Bsupply an acceleration voltage of 1 though 1.5 kV to the correspondingfirst and second FAB sources 303A and 303B.

[0081] The control unit 360 controls respective units in the laminationequipment 3 to perform the process in which the thin film formed on thesubstrate 400 with interposition of the releasing layer is bonded on thesurface of the stage 302 with interposition of the sacrifice layer, aplurality of thin films separated from the substrate are bonded andlaminated successively on the thin film to form a micro-structure basedon programs stored in the memory 361.

[0082]FIG. 4 shows a diagram for describing the bonding strength betweenthe sacrifice layer, thin film, and releasing layer. Assuming that thebonding strength between the releasing layer 401 and the thin layer 4 ais represented by f₁, the bonding strength between thin films 4 a and 4a is represented by f₂, and the bonding strength between the thin film 4a and the sacrifice layer 370 is represented by f₃, then the material ofthe sacrifice layer 370, releasing layer 401, and thin film 4 a isselected so that the order of the strength is in the relation f₂>f₃>f₁.As the result, the thin film 4 a formed on the substrate 400 withinterposition of the releasing layer 401 is bonded to the sacrificelayer 370 on the stage 302 or bonded to the thin film 4 a transferredalready on the stage 302 with sufficient strength, and can be separatedfrom the substrate 400 and transferred to the stage 302 side.

[0083] Next, operations of the manufacturing system 1 in accordance withthe first embodiment are described with reference to FIG. 5 and FIG. 6.Herein it is assumed that the sacrifice layer 370 is formed previouslyon the stage 302.

[0084]FIG. 5 shows one example of a micro-structure to be manufacturedin the first embodiment. The micro-structure 4 comprises a plurality ofthin films 4 a respectively corresponding to each cross-sectional form.

[0085] FIGS. 6 (a) through (c) show a film deposition process andpatterning process.

[0086] (1) Film deposition

[0087] As shown in FIG. 6(a), by using the film deposition equipment 2A,a thermal oxide film with a thickness of 0.1 μm is grown on the surfaceof a substrate 400 namely an Si wafer as the releasing layer 401, and anAl thin film 402 with a thickness of 0.5 μm is formed on the thermaloxidized film by spattering. High purity Al is used for a sputteringtarget, the sputtering pressure is 0.5 Pa and the temperature of thesubstrate is a room temperature. The film thickness is monitoredcontinuously by a quartz oscillator film thickness meter during filmdeposition, the film deposition process terminates when the filmthickness reaches 0.5 μm. As the result, the film thickness on thesubstrate 400 with distribution within 0.5±0.02 μm is obtained. The filmthickness is the determinant of the resolution in the laminationdirection of the micro-structure obtained finally, and sufficientattention should therefore be paid to the film thickness and filmthickness distribution.

[0088] (2) Patterning

[0089] As shown in FIGS. 6(b) and 6(c), a plurality of thin films 4 arespectively corresponding to each cross-sectional form of themicro-structure 4 shown in FIG. 5 is formed by photolithography. Indetail, positive type photo-resist is coated on the surface of the Althin film 402 formed on the substrate 400, the photo-resist is exposedto light with covering by a photo-mask (omitted from the drawing), theexposed portion of the photo-resist is removed by a solvent, the exposedportion of the thin film 402 is etched, and the unexposed photo-resistis removed by a resist remover leaving the plurality of thin films 4 aon the substrate. When, a plurality (for example three) of alignmentmarks 403 for positioning the substrate 400 in patterning process isalso formed. In FIGS. 6(b) and 6(c), the respective thin films 4 a aredesignated as the first layer through the sixth layer in order ofdiameter from the largest one through smallest one for the purpose ofdescription.

[0090] FIGS. 7(a) through 7(c) and FIGS. 8(d) through 8(f) show thelamination process described hereinafter. In FIG. 7 and FIG. 8, thereleasing layer 401 and sacrifice layer 370 are omitted from thedrawings.

[0091] (3) Introduction of the substrate 400 into the vacuum chamber 300

[0092] The substrate 400 on which the plurality of thin films 4 a areformed is placed and fired on the substrate holder 301 in the vacuumchamber 300 of the lamination equipment 3.

[0093] (4) Evacuation of the internal of the vacuum chamber 300

[0094] When an operator pushes down a starting switch (not shown in thedrawing) of the lamination equipment 3, the control unit 360 performsthe process described hereinafter according to the program stored in thememory 361. First, the control unit 360 controls the vacuum pump 350based on the vacuum value detected by the vacuum gauge 307 to evacuatethe internal of the vacuum chamber 300 to 10⁻⁶ Pa, and the internal ofthe vacuum chamber 300 is brought to the condition of high vacuum orultra-high vacuum.

[0095] (5) Alignment adjustment

[0096] After the evacuation, the control unit 360 performs alignmentadjustment of the stage 302 and the substrate 400 (alignment mark 403).In detail, the control unit 360 controls the X-axis motor 311 and theY-axis motor 321 so as to fetch a mark detection signal from the markdetection unit 306 by moving the stage 302 in the X-direction andY-direction, measures the relative positional relation between thesubstrate 400 and substrate holder 301 based on the mark detectionsignal, and controls the X-axis motor 311, the Y-axis motor 321, and theθ motor 341 so that the stage 302 and alignment mark 403 reach theoriginal position based on the measurement result of the relativeposition relation. The stage 302 is moved in the X-direction and theY-direction respectively by the X-axis motor 311 and the Y-axis motor321, the substrate holder 301 is rotated by the θ motor 341, and thestage 302 and alignment mark 403 reach the original position. Hence,even though the position where the substrate 400 on which the thin films4 a are formed is placed deviates from the correct position, therelative position between the stage 302 and the alignment mark 403 isset correctly.

[0097] (6) Removal of the contaminated layer on the surface to be bondedto the first layer thin film 4 a

[0098] As shown in FIG. 7(a), the control unit 360 drives the X-axismotor 311 and the Y-axis motor 321 based on the detection signal of theX-axis position detection unit 312 and the Y-axis position detectionunit 322, and moves the stage 302 from the original position in theX-direction and Y-direction to position the stage 302 on the first layerthin film 4 a. Then the control unit 360 irradiates an argon atomic beam351 a onto the surface (the surface of the stage 302 and the surface ofthe first layer thin film 4 a) where the first layer thin film 4 ais tobe bonded for FAB treatment. In detail, the control unit 360 performsdriving control on the first and second FAB source driving units 362Aand 362B, operation control on the first and second solenoid valves 352Aand 352B, and flow rate control on the first and second MFCs 353A and353B so that the argon atomic beam 351 a is applied onto the surface ofthe stage 302 and the surface of the first layer thin film 4 a with aprescribed rate for a prescribed time (for example, 5 minutes) . Thefirst and second FAB source driving units 362A and 362B are controlledby the control unit 360 so as to provide an acceleration voltage of, forexample, 1.5 kV to the first and second FAB sources 303A and 303B. Theflow rate of argon gas supplied from the argon gas cylinder 351 iscontrolled by the first and second MFCs 353A and 353B, and argon gas issupplied to the first and second FAB sources 303A and 303B through thefirst and second solenoid valves 352A and 352B. The first FAB source303A irradiates the argon atomic beam 351 a for 5 minutes onto thesurface of the stage 302 which is located off the upper direction at anangle of about 45°. The second FAB source 303B irradiates the argonatomic beam 351 a for 5 minutes onto the surface of the first layer thinfilm 4 a which is located off the lower direction at an angle of about45°. The contaminated layers with a thickness of less than 10 nm on thesurface of the stage 302 and the first thin film 4 a are removedthereby. Such small thickness decrement can be neglected because thenumber of decrement is one figure smaller than the target film thicknessprecision of 0.1 μm of the present invention.

[0099] (7) Bonding of the first layer thin film 4 a

[0100] Next, as shown in FIG. 7(b), the control unit 360 drives thefirst and second withdrawing motors 305A and 305B to rotate the arms304A and 304B in the horizontal direction, and withdraws the first andsecond FAB sources 303A and 303B. The control unit 360 controls theZ-axis motor 331 based on the detection signal of the Z-axis positiondetection unit 332 to elevate the substrate holder 301, the surface ofthe first layer thin film 4 a is forced to be in contact with thesurface of the stage 302, and the contact continues for a prescribedtime (for example, 5 minutes) with a prescribed pressure (for example,50 kgf/cm²). The surface of the first layer thin film 4 a is bonded tothe surface of the stage 302 (sacrifice layer 370) strongly. A tensiletest for evaluation of the bonding strength between the thin film 402and the sacrifice layer 370 shows 50 through 100 Mpa. Preferable surfaceroughness of the thin film 4 a and stage 302 is respectively about 10 nmfor obtaining excellent bonding strength.

[0101] (8) Transfer of first layer thin film 4 a

[0102] Next, as shown in FIG. 7(c), the control unit 360 drives theZ-axis motor 331 based on the detection signal of the Z-axis positiondetection unit 332 to lower the substrate holder 301 to the originalposition shown in FIG. 7(a), and drives the first and second withdrawingmotors 305A and 305B to return the first and second FAB sources 303A and303B to the original position. By lowering the substrate holder 301, thethin film 4 a is separated from the substrate 400 and transferred to thestage 302 side because the bonding strength f₃ between the thin film 4 aand the sacrifice layer on the stage 302 is larger than the bondingstrength f₁ between the thin film 4 a and the releasing layer.

[0103] (9) Removal of a contaminated layer on the surface to be bondedto the second layer thin film 4 a

[0104] Next, as shown in FIG. 8(d), the control unit 360 controls theX-axis motor 311 and the Y-axis motor 321 to move the stage 302 abovethe second layer thin film 4 a, and irradiates again FAB as described inFIG. 7(a). The moving distance of the stage 302 is a distancecorresponding to each thin film 4 a pitch. This FAB irradiation isdifferent from the first FAB irradiation in that the back surface of thefirst layer thin film 4 a (the surface which has been in contact withthe substrate 400) is irradiated for cleaning instead of the surface ofthe stage 302.

[0105] (10) Bonding of the second layer thin film 4 a

[0106] Next, as shown in FIG. 8(e), the control unit 360 withdraws thefirst and second FAB sources 303A and 303B, elevates the substrateholder 301 to bond the second layer thin film 4 a to the first layerthin film 4 a.

[0107] (11) Transfer of the second layer thin film 4 a

[0108] Next, as shown in FIG. 8(f), the control unit 360 lowers thesubstrate holder 301, returns the first and second FAB sources 303A and303B to the original position, and lowers the substrate holder 301. Bylowering the substrate holder 301, the second layer thin film 4 a isseparated from the substrate 400 side and transferred onto the firstthin film 4 a because the bonding strength f₂ between thin films islarger than the bonding strength f₁ between the thin film 4 a and thereleasing layer 401.

[0109] (12) Removal of the sacrifice layer 370

[0110]FIG. 9 shows the state that all the thin films 4 a have beenlaminated. By repeating bonding and transferring of thin films 4 a ofthird layer through sixth layer successively, a micro-structure 4comprising all the laminated thin films 4 a is obtained. Finally thesacrifice layer 370 is removed by etching and the micro-structure 4 isseparated from the stage 302.

[0111] The effect of the above-mentioned first embodiment is describedhereinafter,

[0112] (a) A plurality of thin films 4 a which are components of amicro-structure are formed simultaneously together by film depositionand patterning, the plurality of thin films 4 a are laminated thereforesimply by repeating bonding and transfer processes, thus theproductivity is enhanced significantly. Micro-structures aremanufactured efficiently because once the vacuum chamber 300 isevacuated, a set of irradiation of FAB, bonding, and transfer processescan be performed continuously without breaking the vacuum.

[0113] (b) A plurality of thin films corresponding to eachcross-sectional form of a micro-structure is formed together by oneprocess of film deposition and patterning, it is therefore possible tosave the time required for the whole process significantly.

[0114] (c) By injection molding of plastics using the obtainedmicro-structure 4 as a mold, micro-optical parts such as optical lensesare mass-produced.

[0115] (d) Because the thin film 4 a is bonded to the stage 302 side bysurface activated bonding, it is not necessary to use an adhesive or todissolve the material, and therefore the form and thickness of the thinfilm 4 a will not change when bonding, thus high precision ismaintained.

[0116] In this embodiment, thin films are bonded by surface activatedbonding, however, the thin films may be bonded by bonding with anadhesive, or diffusion bonding with heating.

[0117] In this embodiment, the thin films are patterned after filmdeposition, however, alternatively, a simultaneous film deposition andpatterning, for example, a method using a metal mask, or selective CVDmay be used.

[0118] In this embodiment the Al thin film is formed by spattering,however alternatively, the Al thin film may be formed by resistanceheating vapor deposition or electron beam heating vapor deposition.

[0119] Further, the material used for the thin film is not limited toAl, but alternatively other metals such as tantalum (Ta), copper, orindium may be used, and ceramics such as alumina, aluminum nitride,silicon carbide, or silicon nitride may also be used.

[0120] In this embodiment the case that the substrate holder 301 ismoved in the Z-direction, and the stage 302 is moved in the X-directionand the Y-direction is described, however, a case that both thesubstrate holder 301 and the stage 302 are moved in the Z-direction, acase that the substrate holder 301 is moved in the X-direction and theY-direction, and the state 302 is moved in the Z-direction, or a casethat the substrate holder 301 and the stage 302 have the same structuremay be used.

[0121] A set of processes of film deposition, patterning, bonding, andtransferring may be repeated on every thin film 4 a.

[0122] Next, a manufacturing system in accordance with the presentinvention will be described hereinafter. The manufacturing system isprovided with a film deposition equipment, a patterning equipment, and alamination equipment like the first embodiment, but different in thatthe film deposition equipment and patterning device are structured so asto form a plurality of first thin films corresponding to each crosssectional form of a micro-structure by a lift off method, and differentin that a polishing device not shown in the drawing for polishing thesurface of a substrate by CMP (Chemical Mechanical Polishing) isprovided in order to form the second thin film made of the differentmaterial from that of the first thin film and having the same thicknessas that of the first thin film around the first thin film.

[0123] Next, operations of the manufacturing system in accordance withthe second embodiment is described with reference to FIG. 10 and FIG. 11hereinafter.

[0124]FIG. 10 shows a micro-pulley namely micro-structure 4 to bemanufactured in the second embodiment, FIG. 10(a) is an explodedperspective view and FIG. 10(b) is a longitudinal cross-sectional view.The micro-structure 4 shown in the drawing is composed of the firstlayer through twentieth alumina thin films 4 a, and has a structure thata shaft 41 provided with flanges 40 and 40 on both ends thereof isinserted into an opening 43 a of the pulley 43 provided with collars 42and 42.

[0125]FIG. 11 shows film deposition and patterning processes.

[0126] As shown in FIG. 11(a), by using the film deposition equipment, athermal oxide film with a thickness of 0.1 μm is grown on the surface ofthe substrate 400 namely an Si wafer as the releasing layer 401. Then,photo-resist 404 is coated on the releasing layer 401 over the entiresurface, portion of the photo-resist corresponding to eachcross-sectional form of the micro-structure 4 is separated by patterningof exposure and development, and the first thin film 402A with athickness of 1 μm made of alumina (Al₂ 0 ₃) is deposited over the entiresurface using the film deposition equipment.

[0127] Next, as shown in FIG. 11(b), the residual photo-resist 404 isremoved together with the first thin film 402A formed thereon (lift offmethod). The residual first thin film 402A is the thin film 4 a to bethe component of the micro-structure 4.

[0128] Then, as shown in FIG. 11(c), the second thin film 402Bconsisting of aluminum (Al) with a thickness of 1.1 μm is formed byspattering using the film deposition equipment. At this stage, the firstthin film 402A is covered over the entire surface with the second thinfilm 402B. In this embodiment, the combination of the first thin film402A of Al₂ 0 ₃ and the second thin film 402B of Al is selected becausethese materials are bonded easily each other by surface activatedbonding and selectively removable.

[0129] Next, as shown in FIG. 11(d), the surface of the second film 402Bis polished to remove the second thin film 402B by CMP method using thepolishing equipment until the first thin film 402A (4 a) is revealed.The thickness of both the Al ₂ 0 ₃ thin film and Al thin film 402Bbecomes 1 μm. The surface roughness of the Al₂ 0 ₃ thin film 4 a isabout 10 nm like the stage 302. The roughness helps obtain a highbonding strength f₂ between the thin films 4 a and 402B.

[0130]FIG. 12 is a plan view corresponding to FIG. 11(d) During patternforming shown in FIG. 12, a plurality (for example, three) of alignmentmarks 403 are formed.

[0131] Further, as shown in FIG. 11(e), the second thin film 402Bbetween each pattern is removed by normal photolithography or scribingusing the patterning device to form a partition groove 405, and eachcross-sectional element 4 b is separated.

[0132]FIG. 13 is a plain view corresponding to FIG. 11(e). The thin film4 a and the second thin film 402B both having the same thickness whichare to be components of the micro-structure 4 are now arranged. In thisembodiment, every cross-sectional element 4 b which is to structure onemicro-structure 4 is arranged regularly in rows and columns.

[0133] Next, as in the first embodiment, the substrate 400 on which aplurality of thin films 4 a are formed is introduced into the vacuumchamber of the lamination equipment, and then evacuation of the vacuumchamber, alignment adjustment, removal of contaminated layers, thin filmbonding, and transfer are performed.

[0134]FIG. 14 shows a laminated layer comprising the first layercross-sectional element 4 b through the twentieth layer cross-sectionalelement 4 b. In this drawing, the shaded portion shows the thin film 4 aconsisting of Al₂ 0 ₃ and the non-shaded portion shows the second thinfilm 402B consisting of Al. By repeating the above-mentioned processes,the cross-sectional elements 4 b of the first layer through twentiethlayer are laminated on the stage 302 with interposition of the sacrificelayer 370. When the lamination is completed, the appearance is seemed tobe a rectangular parallelepiped of Al, and the pulley 43, the shaft 41and two fringes 40 consisting of Al₂O₂ are imbedded internally. Finally,the Al rectangular parallelepiped is soaked in an etching solution fordissolving Al to remove only the second thin film 402B consisting of Al,and the sacrifice layer 370 is removed, hence the micro-pulley 43combined with the shaft 41 consisting of Al₂O₃ is completed.

[0135] According to the second embodiment, effects described hereinafterare obtained.

[0136] (a) As shown in FIG. 10, a micro-structure comprising a pluralityof complex combined parts can be manufactured. Because the first thinfilm 4 a of Al₂O₃ and the second thin film 402B of Al having the samethickness are laminated simultaneously, the micro-structure can belaminated correctly even though the micro-structure 4 has an overhangportion (A in FIG. 10(b)) or separate portion (B in FIG. 10(b), furtherthe small gap (G in FIG. 10(b)) between the shaft 41 and pulley 43 ismaintained correctly.

[0137] (b) A micro-structure in the form of a micro-gear can bemanufactured.

[0138]FIG. 15 shows a micro-gear, FIG. 15(a) is an exploded perspectiveview, and FIG. 15(b) is a longitudinal cross-sectional view. Themicro-structure 4 shown in FIG. 15 is composed of thin films 4 a of thefirst layer through twentieth layer and the micro-structure has astructure that a shaft 41 provided with flanges 40 and 40 on both sidesis inserted into an opening 43 a of the micro-gear 44.

[0139] (c) Not only can a micro-structure consisting of a metal or aninsulator be formed directly but also a micro-structure having a complexstructure comprising a plurality of combined components can bemanufactured, and assembling work for manufacturing micro-structures issignificantly reduced.

[0140] In this embodiment, the case that combination of ceramics andmetal namely Al₂O₃ for the first thin film and Al for the second thinfilm is described, however, alternatively, combinations, for example, acombination of a metal and a ceramics such as Al and Al₂O₃, acombination of a metal and another metal such as Ta and Al, or, Al andCu, and a combination of two kinds of ceramics such as alumina andsilicon nitride, may be used. This combination is determined byconsidering the bondability each other and capability of selectiveetching.

[0141] CMP method is used in this embodiment, however, a method in whicha thin film is deposited under precise thickness control and theexclusive pattern having the same film thickness is formed by patterningthrough two photolithography may be used.

[0142] The second thin film is removed by etching after all thecross-sectional elements 4 b are laminated in this embodiment, however,a method in which the first thin film is formed of a material which iseasy to remove and then the first thin film is removed may be used. Amold composed of the second thin film having an inside configurationcomplementary to the target micro-structure is obtained thereby, andthen micro-structures consisting of plastics can be mass-produced byinjection molding, cast molding, or press molding using this mold.

[0143]FIG. 16 and FIG. 17 show a thin film deposition substrate inaccordance with the third embodiment. The thin films 4 a of the firstlayer through twentieth layer are formed continuously and separately onthe substrate 400 in the second embodiment, but in the third embodiment148 chips having a size of 10 mm square is formed on one silicon waferhaving a size of 6 inches, and about 7,000 thin films 4 a having thesame thickness are arranged two-dimensionally with a 120 μm pitch oneach chip C. In FIG. 16, a pattern shown in FIG. 17(a) is formed onrespective chips C₁, C₂, C₁₉, and C₂₀, a pattern shown in FIG. 17(b) isformed on respective chips C₃ and C₁₈, a pattern shown in FIG. 17(c) isformed on respective chips C₄, C₅, C₆, C₁₅, C₁₆, and C₁₇, and a patternshown in FIG. 17(d) is formed on respective chips C₇ through C₁₄.

[0144]FIG. 18 shows a laminated layer of chips C composed of the firstlayer to twentieth layer. The second thin film 402B in the chip C isremoved and the sacrifice layer 370 is removed by etching, thereby 7,000micro-structures 4 shown in FIG. 10 are obtained simultaneously, 49,000micro-structures 4 are obtained from one wafer, as the result,micro-structures can be mass-produced. In this embodiment, an embodimentthat one type of micro-structures is arranged in a chip, but a pluralityof different types of micro-structures having different flange diametersand pulley diameters may be arranged.

[0145]FIG. 19 shows a patterning equipment 2B in accordance with thefourth embodiment of the present invention. The fourth embodiment hasthe same structure as the first embodiment excepting the patterningequipment 2B. The patterning equipment 2B has a vacuum chamber 20, andin the vacuum chamber 20 an ion beam generator 22 and a deflectionelectrode 23 for deflecting an ion beam 21 emitted from the ion beamgenerator 22 based on slice data of the micro-structure are provided, athin film 402 is formed on a substrate 400 with interposition of areleasing layer 401 as shown in FIG. 19, then the substrate 400 on whichthe thin film 402 is formed is introduced into the vacuum chamber 20,and unnecessary portions or circumference of the thin film 402 isremoved by focused ion beam (FIB) method. In this embodiment,circumference is removed. “FIB method” generally means a method thatvapor of gallium (Ga) is accelerated by an electric field and focused toa thin beam, and the beam is scanned by applying a voltage to adeflection electrode and applied onto desired portions on the target,such a method is generally used for analysis or observation of a sampleor used for fine working as in this embodiment.

[0146] Next, operations in this embodiment is described with referenceto FIG. 20.

[0147]FIG. 20 shows a micro-structure 4 to be manufactured in the fourthembodiment. The micro-structure 4 has a drum configuration composed ofthin films first layer to n-th layer. As in the first embodiment, areleasing layer 401 is formed on a substrate 400, and an Al thin film402 having a thickness of 0.5 μm is deposited. Next, as shown in FIG.19, the substrate 400 is introduced into the vacuum chamber 20, and theAl thin film 402 is selectively removed by FIB method. Though not onlythe Al layer is removed but also the substrate surface is slightlyremoved because the etching in the depth direction is controlled not soprecisely in removal process by FIB method, the slight removal of thesubstrate 400 causes no problem because of no micro-parts in the lowerlayer.

[0148]FIG. 21 is a plan view for showing the structure after patterning.In the drawing, 405 is a partition groove formed by FIB method. The formof patterning is that regions S₁, S₂, S₃, S₄, . . . having respectiveforms corresponding to each cross-sectional form of the micro-structure4 are arranged with a space between them in the respectivecross-sectional elements 4 b. A cross-sectional element 4 b has anarbitrary form with a size larger than the maximum cross-sectional areaof the micro-structure 4 to be manufactured, and is rectangular in thisembodiment. Cross-sectional elements 4 b each of which has across-sectional pattern of the micro-structure to be manufactured arearranged two-dimensionally on the entire surface of the substrate 400.

[0149] Following the process described herein above, the substrate onwhich a plurality of cross-sectional elements 4 b are formed isintroduced into the vacuum chamber 300 of the lamination equipment 3,and by repeating processes of bonding and transfer the micro-structure 4composed of the plurality of laminated cross-sectional elements 4 b iscompleted.

[0150]FIG. 22 shows laminated cross-sectional elements 4 b of the firstlayer though the n-th layer. The micro-structure 4 composed of centralregions S₁, S₂, S₃, S₄, . . . of the respective cross-sectional elements4 b is obtained by etching-removing the sacrifice layer 370.

[0151] According to the above-mentioned fourth embodiment, because FIBthin film patterning allows the process to be performed without aphoto-mask for patterning the thin films, the time required formanufacturing is shortened. The pressure can be kept constant whenlaminating thin films because the areas of all the cross-sectionalelements 4 b are substantially the same. Only the grid region forseparating each cross-sectional element 4 b and the border region ineach cross-sectional element 4 b are removed, and therefore the timerequired for processing is saved. The drawing precision of about 0.1 μmis obtained, precise forming of a micro-structure is realized.

[0152] FIB is used in the above-mentioned embodiment, however,alternatively, an electron beam may be used.

[0153]FIG. 23 shows a manufacturing system of micro-structures inaccordance with the fifth embodiment of the present invention. Themanufacturing system 1 is provided with a film deposition equipment 2Afor depositing a thin film on a substrate, an ion implantation device 2Cfor implanting ions onto a region corresponding to each cross-sectionalform of a target micro-structure out of thin films formed by the filmdeposition equipment 2A, and a lamination equipment 3 for laminatingonto a plurality of regions where ions are implanted by surfaceactivated bonding with irradiation of FAB in the vacuum chamber.

[0154] Next, operations in the manufacturing system 1 in accordance withthe fifth embodiment are described with reference to FIG. 24 and FIG.25.

[0155]FIG. 24(a) through FIG. 25(d) and FIG. 25(e) through FIG. 25(h)are drawings to show the manufacturing processes in accordance with thefifth embodiment.

[0156] As shown in FIG. 24(a), a releasing layer 401 of an SiO₂ film isformed on the surface of the substrate of a silicon wafer using the filmdeposition equipment 2A, and a non-doped polycrystalline Si (poly-Si)thin film 410 is formed thereon by low pressure chemical vapordeposition (LPCVD). Because the final micro-structure is formed from thepoly-Si thin film 410, sufficient attention should be paid to the filmthickness and film thickness distribution. In this embodiment, thepoly-Si thin film 410 with a thickness of 1.0±0.02 μm is formed. An SOIwafer (Silicon On Insulator) may be used instead of the SiO₂ film andpoly-Si thin film 410 formed on the substrate 400. Next, a siliconnitride film 411 with a thickness of 0.5 μm is formed on the surface ofthe poly-Si thin film 410 by LPCVD, and a window 411 a corresponding tothe cross-sectional form of the micro-structure is provided by theconventional photolithigraphy.

[0157] Next, as shown in FIG. 24(b), the substrate 40 is introduced intothe ion implantation equipment 2 c, boron (B) is implanted up to a highconcentration, for example, of 3×10E19 [cm⁻³] or higher. After animplanted mask is removed, annealing is performed in a nitrogenatmosphere to change the ion implanted region to a high concentration p⁺Si region 410 a namely impurity diffused region, which is served as alatent image.

[0158] As the result, as shown in FIG. 24(c), the substrate 400 having astructural portion of the micro-structure comprising p⁺ Si region 410 aand a peripheral portion comprising non-doped Si region 410 iscompleted.

[0159] Substrates 400 shown in FIG. 24(c) required to form themicro-structure are prepared by applying the above-mentioned process tothin films corresponding to other cross-sectional forms of themicro-structure.

[0160] Next, as shown in FIG. 24(d), the substrate 400 on which p⁺ Siregion 410 a corresponding to the cross-sectional form of the firstlayer and the substrate 400 on which p⁺ Si region 410 a corresponding tothe cross-sectional form of the second layer are bonded together. Indetail, two substrates 400 and 400 are introduced into the vacuumchamber of the lamination equipment 3, the surface is cleaned by FABirradiation as in the first embodiment, the position of the twosubstrates 400 and 400 is adjusted, both substrates are bonded togetherwith a pressure, and the substrates 400 and 400 are bonded by surfaceactivated bonding. Alternatively, the conventionally well known waferbonding may also be applied instead of surface activated bonding. In the“wafer bonding” process, two Si wafers are cleaned sufficiently to makethe surface hydrophilic and superimposed, and heat-treated at about1,000° C. to bond strongly. In this method, because impuritydistribution of the region formed by ion implantation is changed due tore-diffusion as the result of the high temperature heat treatment, andthe impurity distribution change causes change of the form of themicro-structure, it is necessary that the size of the implantation maskpattern is corrected previously for the change. Surface activatedbonding by FAB is therefore preferable because such correction isunnecessary.

[0161] Next, as shown in FIG. 25(e), the back side of the substrate 400having the surface on which the p⁺ Si region 410 a corresponding to thecross-sectional form of the second layer is formed is polished until thereleasing layer 401 of SiO₂ is exposed. Because the releasing layer 401can be detected when it is exposed, it is avoided that the Si thin film410 of the bonding interface is undesirably polished excessively in thepolishing process.

[0162] Next, as shown in FIG. 25(f), the releasing layer 401 is removedby etching with buffered hydrofluoric acid, and a semi-finished producthaving two laminated Si thin films 410 is completed.

[0163] Subsequently, the above-mentioned processes (d) through (f) arerepeated to form a semi-finished product having as many laminated Sithin films 410 as required.

[0164] Next, as shown in FIG. 25(h), the Si thin film 410 around the p⁺Si region 410 a is removed by etching with a KOH solution or EDP(ethylenediamine pyrocatechol) solution in the development process. Thesignificant difference of the etching rate between non-doped Si anddoped Si to these solutions allows the non-doped Si to be removedselectively. Though not shown in the drawing, the back side of thesubstrate 400 may be protected with a silicon nitride film, for example.Finally the releasing layer 401 on the substrate 400 is removed byetching with a buffered hydrofluoric acid, then the completedmicro-structure 4 is separated from the substrate 400.

[0165] According to the fifth embodiment, there are the dopedmicro-structure structural portion and the non-doped portion surroundingthe doped portion both having the same thickness, the surroundingportion functions as a support, an assembled part which has a complexform with an overhang can be therefore formed. The ion-implanted regionis formed as a latent image, and the latent image is developed with anEDP solution after lamination, alternatively the latent image formingmethod and development method other than the above-mentioned methodssuch as selective exposure of photo-resist and development treatmentusing a developing solution may be used.

[0166] In this embodiment, a silicon nitride film 411 is used as theimplanting mask during the ion implanting process, alternatively asilicon oxide film or photo-resist may be used.

[0167] Embodiments

[0168] Embodiments of the releasing layer to be formed on a substratesurface are described hereinafter.

[0169] (Embodiment 1)

[0170] Because, by using fluoro polymer (CYTOP, product of Asahi GlassCompany) as the releasing layer, a thin layer can be formed on asubstrate by spin-coat method, and surface energy is very small(generally very water repellent), the adhesion of the film formed on thesurface is very low (about 1 MPa), and the film is suitable as thereleasing layer. After spin-coating of a coupling agent (to improve theadhesion on a substrate) on an Si wafer or glass substrate, a film withthickness of about 2 μm of fluoro polymer (CYTOP) is spin-coated andbaked at the maximum temperature of 300° C. to form a releasing layer.

[0171] (Embodiment 2)

[0172] By using fluorinated polyimide (OPI-N1005, product of HitachiChemical Co., Ltd.) as the releasing layer a releasing layer can beformed by spin-coat method, and polyimide has a glass transitiontemperature higher than fluoro polymer (CYTOP), and the maximumtemperature of film deposition and patterning process is higher. Aftercoating of a coupling agent, a film with a thickness of about 5 μm offluorinated polyimide (OPI-N1005) is spin-coated on a substrate, andbaked at the maximum temperature of 350° C. to form a releasing layer.

[0173] (Embodiment 3)

[0174] It is confirmed that a fluorinated surface layer obtained byexposing the substrate surface to a gas containing fluorine atomexhibits the same effect. Specifically, an Si wafer, an Si wafer onwhich oxide film is formed, or a glass substrate or these substratescoated with non-fluorinated polyimide introduced into a vacuum equipment(dry etching machine), and plasma treatment is applied using CF₄ gas(gas flow rate of 100 sccm, discharging power of 500 W, pressure of 10Pa, and time of 10 minutes), this process results in reduced adhesionstrength with the thin film. The same process is also effective usingSF₆ gas.

[0175] As described hereinabove, according to the present invention,because thin films are used as starting material, and a plurality ofthin films are laminated by bonding, thus the dimensional precision ishigh and high resolution in the lamination direction is realized.

[0176] Because a micro-structure composed of thin films consisting of ametal or an insulator can be formed, it is possible to manufacturemicro-structures directly from a metal or an insulator such as ceramics.

[0177] By applying a process in which the first thin film and secondthin film are formed with the same film thickness, a plurality of thinfilms are laminated, and then the first thin film or second thin film isremoved selectively, a micro-structure having a plurality of structuralelements is formed simultaneously, and thus the steps of themanufacturing and assembling work of micro-structures are significantlyreduced.

What is claimed is:
 1. A micro-structure comprising a plurality oflaminated thin films having prescribed two-dimensionally patternedforms.
 2. The micro-structure as claimed in claim 1 , wherein surfacesof said plurality of thin films are bonded together in direct contact.3. The micro-structure as claimed in claim 1 , wherein said wholemicro-structure is composed of only the composition of said plurality ofthin films.
 4. The micro-structure as claimed in claim 1 , wherein saidmicro-structure is composed of a plurality of structural elements whichare relatively movable and combined inseparably.
 5. A manufacturingmethod of micro-structures comprising a first step for forming aplurality of thin films having prescribed two-dimensionally patternedforms on a substrate, and a second step for forming the micro-structureby laminating and bonding said plurality of thin films on a stage. 6.The manufacturing method of micro-structures as claimed in claim 5 ,wherein said plurality of thin films are formed on said substrate withinterposition of spaces between thin films in said first step.
 7. Themanufacturing method of micro-structures as claimed in claim 5 , whereinsaid plurality of thin films are transferred from said substratesimultaneously, and said plurality of thin films are laminatedsimultaneously on different positions on said stage in said second step.8. The manufacturing method of micro-structures as claimed in claim 5 ,wherein a plurality of thin films having the same two-dimensionalpattern are formed on said substrate with interposition of spaces insaid first step, and said plurality of thin films having the sametwo-dimensional pattern are separated simultaneously in said secondstep.
 9. The manufacturing method of micro-structures as claimed inclaim 5 , wherein a support thin film is formed surrounding thin filmshaving said two-dimensional pattern with interposition of a space onsaid substrate in said first step, said plurality of thin films and saidsupport thin film are separated simultaneously from said substrate andsaid plurality of thin films and said support thin film are laminatedsimultaneously on said stage in said second step, and after the secondstep, a third step in which a support formed of said laminated supportthin films surrounding said micro-structure is removed is provided. 10.The manufacturing method of micro-structures as claimed in claim 5 ,wherein said first step is a step in which a thin film is deposited onsaid substrate by vacuum vapor deposition or spin coating, and saidplurality of thin films are formed by patterning said thin film into aprescribed two-dimensional pattern.
 11. The manufacturing method ofmicro-structures as claimed in claim 10 , wherein said patterningprocess is a process in which a circumference of said two-dimensionalpattern or unnecessary portion other than said two-dimensional patternis removed by irradiating it with a focused ion beam or electron beam.12. The manufacturing method of micro-structures as claimed in claim 10, wherein said patterning process is the lithography process includingresist pattern forming and etching.
 13. The manufacturing method ofmicro-structures as claimed in claim 5 , wherein said plurality of thinfilms are bonded by surface activated bonding in said second step. 14.The manufacturing method of micro-structures as claimed in claim 5 ,wherein said second step includes a process for cleaning the bondedsurface of said stage and said plurality of thin films in a vacuumchamber.
 15. The manufacturing method of micro-structures as claimed inclaim 14 , wherein said cleaning process is a process in which saidbonded surface is irradiated with a particle beam.
 16. The manufacturingmethod of micro-structures as claimed in claim 5 , wherein a sacrificelayer which can be selectively removed after forming saidmicro-structure by laminating said plurality of thin films is formedpreviously on the surface of said stage as an interface between saidthin film and said stage.
 17. The manufacturing method ofmicro-structures as claimed in claim 5 , wherein a releasing layer isformed previously on the surface of said substrate as an interfacebetween said substrate and said thin film.
 18. The manufacturing methodof micro-structures as claimed in claim 17 , wherein said releasinglayer is formed by vacuum vapor deposition or coating offluorine-containing material or by exposing the surface of saidsubstrate to discharge of a gas containing fluorine atoms to fluoridizethe substrate surface.
 19. A manufacturing method of micro-structurescomprising; a first step for forming a plurality of first thin filmshaving a prescribed two-dimensional pattern on a substrate, and forminga plurality of second thin films composed of different material fromthat of said first thin films and having the same film thickness as saidfirst thin film around said plurality of first thin films to form aplurality of composite thin films composed of said first thin films andsaid second thin films, a second step for forming a laminate including amicro-structure by separating said plurality of composite thin filmsfrom said substrate and subsequently by laminating and bonding saidplurality of composite thin films on a stage, and a third step forremoving said first thin films or said second thin films out of saidlaminate to obtain said micro-structure.
 20. The manufacturing method ofmicro-structures as claimed in claim 19 , wherein said plurality offirst thin films are formed on said substrate with interposition ofspaces in said first step.
 21. The manufacturing method ofmicro-structures as claimed in claim 19 , wherein a plurality of saidcomposite thin films are transferred simultaneously from said substrateand said plurality of composite thin films are laminated simultaneouslyat different positions on said stage in said second step.
 22. Themanufacturing method of micro-structures as claimed in claim 21 ,wherein a plurality of composite thin films having the sametwo-dimensional pattern are formed on said substrate with interpositionof spaces between said thin films in said first step, and said pluralityof composite thin films having the same two-dimensional pattern aretransferred simultaneously in said second step.
 23. The manufacturingmethod of micro-structures as claimed in claim 19 , wherein said firststep includes a process in which a thin film is formed on said substrateby vacuum vapor deposition or spin coating, and said plurality of firstthin films are formed by patterning said thin film into a prescribedtwo-dimensional pattern.
 24. The manufacturing method ofmicro-structures as claimed in claim 23 , wherein said patterningprocess is a process in which the circumference of said two-dimensionalpattern or unnecessary portion other than said two-dimensional patternis removed by application of a focused ion beam or an electron beamthereto.
 25. The manufacturing method of micro-structures as claimed inclaim 23 , wherein said patterning process is the photolithographyincluding resist pattern forming and etching.
 26. The manufacturingmethod of micro-structures as claimed in claim 19 , wherein said firststep includes a process in which said plurality of first thin films areformed and said second thin films are formed on said substrate on whichsaid plurality of first thin films are not formed, and then the filmthickness of said first thin films and the second thin films isequalized by polishing the surface until the film thickness of saidfirst thin films and said second thin films is made equal.
 27. Themanufacturing method of micro-structures as claimed in claim 19 ,wherein said plurality of composite thin films are bonded by surfaceactivated bonding in said second step.
 28. The manufacturing method ofmicro-structures as claimed in claim 19 , wherein said second stepincludes a process for cleaning the bonding surface of said stage andsaid plurality of composite thin films in a vacuum chamber.
 29. Themanufacturing method of micro-structures as claimed in claim 28 ,wherein said cleaning process is a process in which said bonded surfaceis irradiated with a particle beam.
 30. The manufacturing method ofmicro-structures as claimed in claim 19 , wherein a sacrifice layerwhich can be removed after forming said laminate is formed previously onthe surface of said stage as an interface between said composite thinfilm and said stage by laminating said plurality of composite thinfilms.
 31. The manufacturing method of micro-structures as claimed inclaim 19 , wherein a releasing layer is formed previously on the surfaceof said substrate as an interface between said substrate and saidcomposite thin film.
 32. The manufacturing method of micro-structures asclaimed in claim 31 , wherein said releasing layer is formed by vapordeposition or coating of fluorine-containing material, or by exposingthe surface of said substrate to discharge of a gas containing fluorineatom to fluoridize the surface of said substrate.
 33. The manufacturingmethod of micro-structures as claimed in claim 20 , wherein saidmicro-structure is composed of a plurality of independent structuralelements, and in said first step said plurality of first thin films areformed so that said plurality of structural elements which are assembledin the form of said micro-structure are contained in said laminate whenlamination of said plurality of composite thin films in said second stepis completed.
 34. A manufacturing method of micro-structures comprising;a first step for forming a thin film respectively on a plurality ofsubstrates and forming a plurality of latent images having a prescribedtwo-dimensional pattern on each said thin film formed on said pluralityof substrates, a second step for bonding said thin films each other onwhich said latent images are formed, a third step for removing onesubstrate out of a pair of said substrates having said thin films bondedeach other, a fourth step for laminating a plurality of thin films byrepeating said second step and said third step, and a fifth step fordeveloping said latent images out of said plurality of laminated thinfilms.
 35. The manufacturing method of micro-structures as claimed inclaim 34 , wherein said latent images are formed by diffusion ofimpurity into said substrate.
 36. A manufacturing apparatus ofmicro-structures provided with a substrate holder on which a substratehaving a plurality of thin films are formed thereon having a prescribedtwo-dimensional pattern provided in a vacuum chamber, a stage disposedfacing said substrate holder in said vacuum chamber for supporting athree-dimensional structure formed by laminating said plurality of thinfilms, moving means for transferring at least either of said substrateholder and said stage to position said stage successively on saidplurality of thin films, and control means for controlling said movingmeans to separate said plurality of thin films from said substrate, tolaminate and bond said plurality of thin films on said stage so as toform a micro-structure.
 37. The manufacturing apparatus ofmicro-structures as claimed in claim 36 , wherein said moving means isprovided with a moving mechanism for moving relatively said substrateholder and said stage at least in three axis directions.
 38. Themanufacturing apparatus of micro-structures as claimed in claim 36 ,wherein said vacuum chamber is provided with irradiation means forapplying an atomic beam or ion beam onto the surface of said stage to bebonded or said thin film in order to clean the surface.